Aussie planes 5m from mid-air crash disaster

Two aircraft came within 5m of colliding mid-air in a terrifying incident near Darwin, the nation's transport safety authority found.

The Australian Transport Safety Bureau (ATSB) has handed down its report into the near-miss involving two Cessna aircraft that had taken off one minute apart at Darwin Airport in 2017.

Both planes were bound for the remote community of Wadeye in the Northern Territory.

According to the ATSB's report into the December 3, 2017 incident, the planes lost sight of each other shortly after takeoff.

But about 46km southwest of the airport, the plane operated by Hardy Aviation, with two passengers on board, swooped dramatically in front of the other Cessna, operated by Chartair.

The ATSB's report said the planes were believed to have come less than 5m away from each other.

The two Cessna planes, one carrying a pilot and two passengers, and the other with only the pilot on board, came within 5m of each other while flying out of Darwin. Picture: ATSB

"The pilot of (the Chartair plane) commented that as soon as he made that request to deviate three nautical miles right of track, (the Hardy Aviation plane) came from the left top corner of his windshield across the nose to the bottom right in front of him and filled the windscreen," the report said.

"He estimated the two aircraft passed 3-4m apart."

Meanwhile the Hardy Aviation pilot said he was "surprised" by the proximity of the other plane when it suddenly came in its 5 o'clock position.

"He and the passengers in (the Hardy Aviation plane) estimated the aircraft came within 5m of each other," the report said.

A review of the radar data by the ATSB found the positions of the planes were different from what was advised by air traffic control in Darwin.

After the near-miss, both planes continued to fly safely to their destination.

In its findings the ATSB said the "approach controller did not verify the initial altitude of (the Chartair plane), which was outside the allowable 200-foot (61m) tolerance".

"That resulted in the two aircraft being significantly vertically closer than displayed and, in turn, the controller issuing a safety alert after the near collision had occurred," the report said.

The ATSB also found after the Chartair pilot lost sight of the other plane and advised air traffic control he "took no further action to ensure segregation between the aircraft".

The ATSB said it was mainly the responsibility of pilots to avoid collisions between aircraft operating under visual flight rules (VFR).

"While air traffic controllers can provide traffic information to pilots of VFR flights, see-and-avoid is the primary means of preventing collisions between VFR aircraft," the report said.

It urged pilots of small aircraft to fit collision avoidance technology to increase awareness of other aircraft traffic and avoid similar near misses.